Technical Abstract:
A series of experiments was conducted to examine whether sheep select herbage of higher water soluble carbohydrates (WSC) content. In late November 1998, a field of \italicize{Phalaris aquatica} at the research facility near Canberra, Australia, was partitioned and cut at either 0530h (M) or at 1130h (N). The cut material was conditioned that afternoon and compressed into rectangular bales the next morning. Maximum temperatures on the days of cutting and baling were 36 and 33C, respectively. Each hay was assayed for WSC (M 53.6 g/kg; N 78.7 g/kg DM) in duplicate and about 100 kg of each was coarsely chopped. A separate hay of moderate quality was used as a control (C). Each of the three chopped hays was fed to four sheep to determine rate of intake over five 2 minute intervals. Intake rates were 3.1, 5.0, and 2.7 g/min (P =.06) for C, M, and N hay respectively. A replicated 3x3 latin square design was used for the selectivity trials with the treatment being one of three two-hay comparisons (C-M, C-N, M-N). Sheep ate more M than C (difference = 2.9g/min; P < .05), more M than N (3.2g/min; P < .05) and equal proportions of C and N. Reduced intake rate and a harsh feel after grinding for N hay suggested that physical characteristics of the hays influenced selection more than the chemical differences. Samples of the M and N hays were ground through a Christy-Norris mill to pass a 1 mm screen and the ground material was applied to the C hay with sufficient water to cause it to adhere. The three hays were then fed as above with one treatment being the control hay without ground material. Statistically, the sheep made no preference for any hay, but there was a numerical preference for N over both M and C.